1. Field of the Invention
The present invention relates to wireless communication and, more particularly, to an apparatus and method for controlling an uplink transmit power in a wireless communication system.
2. Related Art
Wireless communication systems are widely spread all over the world to provide various types of communication services such as voice or data. In general, the wireless communication system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit (Tx) power, etc.). Examples of the multiple access system include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency division multiple access (SC-FDMA) system, etc.
The proliferation of wireless communication systems has created system interoperability problems, degrades efficiency of spectrum utilization, and increases the cost of communication services. Spurious emissions are emissions which are caused by unwanted transmitter effects such as harmonics emission, parasitic emissions, intermodulation products and frequency conversion products. The spurious emissions may cause interference between adjacent frequency bands.
3rd generation partnership project (3GPP) long term evolution (LTE) is a part of an evolved-universal mobile telecommunications system (E-UMTS). The evolved-UMTS Terrestrial Radio Access (E-UTRA) is the air interface of 3GPP LTE. E-UTRA employs the OFDMA in downlink and employs the SC-FDMA in uplink. E-UTRA supports various frequency bands. Some E-UTRA band may be adjacent to other system's frequency band. In the adjacent E-UTRA band, the spurious emissions by a transmitter may cause interference with the other system's frequency band.
A public safety band (PSB) is a regulated spectrum exclusively to public safety. The PSB may be defined in a 700 MHz or 4.9 GHz band. Police departments, fire departments, emergency medical services and other emergency responders may rely on point-to-point and point-to-multipoint communications systems operating in the PSB. The integrity and reliability of many of these public service networks are critical in emergencies.
When an E-UTRA band is adjacent to the PSB, the interference due to the spurious emissions may be caused. To guarantee the reliability of the PSB, a transmit power needs to be adjusted by taking into account for the spurious emissions.